Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

In situ solidification and in situ chemical oxidation combined in a single application to reduce contaminant mass and leachability in soil

“…Ordinary PC contains up to 6% ferric oxide [5], and iron can activate PS [15]. However, previous studies of PS activation by ISS amendments in various soils have shown that PS activation is not enhanced by the iron in PC [24,26,27], but rather by the increase in temperature and pH that PC and other ISS amendments bring about. Values of pH and temperature are not presented here, but screening studies done on this soil showed that the period of PS disappearance in each reaction scenario coincided with temperatures above 30 C and/or pH values above 11.…”

“…ISCO degrades organic contaminants, particularly the most soluble ones [23,24]. High oxidant doses and multiple injections are often required, and the residual contaminants are not prevented from leaching.…”

“…The more soluble and volatile contaminants are preferentially oxidized by ISCO, and ISS reduces the leachability of the residual contaminants [24,26,27]. PS is typically activated within hours or days [17,24], while ISS cementation reactions continue for weeks [1]. High concentrations of organic contaminants can interfere with cementation reactions [28].…”

“…Related publications by EPRI [26] and Cassidy et al [24] were the first to demonstrate that appropriate doses of ISS amendments can activate PS. A significant portion of the contaminants were chemically oxidized, and the sulfate end-product promoted longterm bioremediation of residual contaminants by native sulfatereducing bacteria.…”

“…The EPRI study [26] tested various ratios of PS: PC for the ability to achieve complete activation of PS in two different soils. Both EPRI [26] and Cassidy et al [24] showed that when PS was activated, the leachability of the residual contaminants not oxidized was greatly reduced compared to treatment with ISS, ISCO, or enhanced bioremediation treatments alone. Subsequent work by Srivastava et al [27] further investigated combining ISCO and ISS (with no bioremediation component).…”